Summary

Newborn hamsters, which are susceptible to the oncogenic activity of both simian vacuolating virus (SV40) and human adenovirus 12, were inoculated with both viruses simultaneously or with the progeny of mixed infection pools prepared in African green monkey kidney cell cultures.

Sixty-three to 80% of the animals developed tumors between 4 and 12 weeks after inoculation, and these tumors histologically were typical of those seen after inoculation of adenovirus 12. Of the remaining animals which did not develop tumors before 12 weeks, almost all had tumors by 16–28 weeks. In contrast to the earlier tumors, these tumors were histologically typical of those produced by SV40. There were no new types of tumors produced after infection by both viruses, and there was no evidence that the tumors produced by either virus had been altered by the presence of the other virus.